Eddie's Lessons
Beginners Programming
Creating an irregular shaped window is achieved with WinAPI calls to user32.dll and gdi32.dll. The first step is to create a window without a caption. This can be achieved with the stylebits commands _WS_POPUP in the addbits parameter and _WS_CAPTION in the removebits paramater, or simply using the window_popup style. It is also advisable to keep the window in the forefront. Do this by using the stylebits command _WS_EX_TOPMOST in the extended bits parameter. Remember that a window without a caption may be closed with Alt-F4.
Note: For more detailed discussion of stylebits, see [Stylebits Corner - An Introduction].
This first demo draws a circle, a rectangle, and some graphic text. The background is never added to the window. Only the actual drawings, including the graphic text, become part of the window. Open a captionless window.
Nomainwin
'Define the Window
WindowWidth = 500
WindowHeight = 500
UpperLeftX = int((DisplayWidth-WindowWidth)/2)
UpperLeftY = int((DisplayHeight-WindowHeight)/2)
Graphicbox #ShapeWindow.gb, 0, 0, 500, 500
Stylebits #ShapeWindow.gb, 0, _WS_BORDER, 0, 0
'Keep the Shaped Window in the Forefront
Stylebits #ShapeWindow, 0, 0, _WS_EX_TOPMOST, 0
Open "Shape Window" for Window_popup as #ShapeWindow
#ShapeWindow "Trapclose [closeShapeWindow]"
Once the window is opened, handles and device controls to both the window and the graphicbox must be obtained.
'Obtain the Handles and Device Controls
hBw = hWnd(#ShapeWindow)
hBgb = hWnd(#ShapeWindow.gb)
hDCw = GetDC(hBw)
hDCgb = GetDC(hBgb)
'The Function
Function GetDC(hW)
Calldll #user32, "GetDC", _
hW as long, _
GetDC as long
End Function
Now you're ready to draw an image. In this first demo, the image will be drawn using API calls. These are the steps in the [drawShape] gosub.
1: The Destination - Define a region to hold the finished window. Because this region will be built upon, start with all 0's for x, y, width and height.
'Original values for hRgn is meaningless
hRgn = RectRegion(0, 0, 0, 0)
'The Function
Function RectRegion(ulx, uly, width, height)
CallDLL #gdi32, "CreateRectRgn", _
ulx as long, _
uly as long, _
width as long, _
height as long, _
RectRegion as long
End Function
2: The Circle - Define the x, y, width and height values for the circle. Select a red brush, paint the designated ellipse, delete the brush.
'hRgn1 = Elliptical Source Region
hRgn1 = EllipticRegion(100, 50, 200, 250)
'Paint the Ellipse Red
brushColor1 = 255 'Red Brush
hBrush1 = createBrush(brushColor1)
Call SelObject hDCw, hBrush1
Call PaintRegion hDCw, hRgn1
Call DelObject hBrush1
'The Functions and Subs
Function RectRegion(ulx, uly, width, height)
CallDLL #gdi32, "CreateRectRgn", _
ulx as long, _
uly as long, _
width as long, _
height as long, _
RectRegion as long
End Function
Function EllipticRegion(ulx, uly, width, height)
CallDLL #gdi32, "CreateEllipticRgn", _
ulx as long, _
uly as long, _
width as long, _
height as long, _
EllipticRegion as long
End Function
Function createBrush(brushColor)
Calldll #gdi32, "CreateSolidBrush", _
brushColor as long, _
createBrush as long
End Function
Sub PaintRegion hDC, hRgn
Calldll #gdi32, "PaintRgn", _
hDC as long, _
hRgn as long, _
null as ulong
End Sub
Sub DelObject hObject
Calldll #gdi32, "DeleteObject",_
hObject as long,_
null as long
End Sub
Sub SelObject hDC, hBrush
Calldll #gdi32, "SelectObject", _
hDC as long, _
hBrush as long, _
null as long
End Sub
Use CombineRgn to add this painted region, hRgn1, to the destination region, hRgn.
'Set hRgn to the Combination of itself and hRgn1
newRgn = CombineRgn(hRgn, hRgn, hRgn1, _RGN_OR)
Now that region hRgn1 is a part of region hRgn, it is no longer needed. Delete that object to free memory.
'Delete hRgn1
Call DelObject hRgn1
3: The Rectangle - Define the x, y, width and height values for the rectangle. Select a blue brush, paint the designated rectangle, delete the brush.
'hRgn2 = Rectangular Source Region
hRgn2 = RectRegion(150, 75, 300, 200)
'Paint the rectangle blue
brushColor2 = 255 * 256^2 'Blue Brush
hBrush2 = createBrush(brushColor2)
Call SelObject hDCw, hBrush2
Call PaintRegion hDCw, hRgn2
Call DelObject hBrush2
Once again, use the API Call CombineRgn to add the pixels of the rectangle hRgn2 to the final destination region hRgn.
'Set hRgn to the Combination of itself and hRgn2
newRgn = CombineRgn(hRgn, hRgn, hRgn2, _RGN_OR)
The hRgn2 rectangle can now be safely deleted to free up space, as it's been added to the shaped window region hRgn.
'Delete hRgn2
Call DelObject hRgn2
4: The newly built region made up of regions hRgn1 and hRgn2 can now be set as the window.
'Set hRgn as the Window
Call SetWindowRgn hBw, hRgn, 1
'The Sub
Sub SetWindowRgn hWnd, hRgn, redrawMode
Calldll #user32, "SetWindowRgn",_
hWnd as long,_
hRgn as long,_
redrawMode as boolean,_
SetWindowRgn as long
End Sub
A word about boolean operands. The combine mode _RGN_AND doesn't mean either/or. It means both must be true. Only the area that's common to both regions will be added. The combine mode _RGN_OR means any region that is a part of one or the other. _RGN_XOR means any region that is a part of one region, but not of both regions. It is also possible to isolate a region not common to both areas using _RGN_DIFF. This diagram might help explain further. Note that the borders in this diagram are for illustrative purposes only and will not show in the actual program.
The SetBkMode of #gdi32 can be called to achieve a transparent background for text. Text can then become part of the window.
'Set background to Transparent
Call SetBkMode hDCgb, 1
ReleaseDC is again called to release memory.
'Release memory
Call ReleaseDC hBgb, hDCbg
Graphics text is accomplished with native Liberty BASIC code.
'Format Text
#ShapeWindow.gb, "Font Courier_New 14 Bold"
#ShapeWindow.gb, "Color Black; Place 120 150"
#ShapeWindow.gb, "\Alt-F4 to Close"
Wait
Run your program and a shaped window appears. Close the window with Alt-F4 or include a button for closure. The window will stay on top of other windows, but it is possible for the window to lose focus. If this happens, click on the window before pressing Alt-F4.
The complete program is included in the files archive as ShapedDemo1.bas
The second demo creates a nonrectangular window from a bitmap in memory. This demo draws the image, but you could just as easily load the bitmap from file using Loadbmp. The stylebits _WS_BORDER is used to remove the graphicsbox border.
'Define the Window
WindowWidth = 250
WindowHeight = 250
UpperLeftX = int((DisplayWidth-WindowWidth)/2)
UpperLeftY = int((DisplayHeight-WindowHeight)/2)
Stylebits #ShapeWindow.gb, 0, _WS_BORDER, 0, 0
Graphicbox #ShapeWindow.gb, 0, 0, 250, 250
Stylebits #ShapeWindow, 0, 0, _WS_EX_TOPMOST, 0
Open "Shape Window" for Window_Popup as #ShapeWindow
#ShapeWindow "Trapclose [closeShapeWindow]"
'Obtain the Handles and Device Controls
hBw = hWnd(#ShapeWindow)
hBgb = hWnd(#ShapeWindow.gb)
hDCw = GetDC(hBw)
hDCgb = GetDC(hBgb)
'Draw the Shape
#ShapeWindow.gb, "Down; Fill Black"
Gosub [drawShape]
Wait
Once again, after the shapes are drawn, the background color is set to transparent before writing the graphic text. A region to hold the contents of the new window is defined.
'Set region to null
hRgn = RectRegion(0, 0, 0, 0)
The shapes are drawn and text is written.
'Draw a Rectangle
#ShapeWindow.gb, "Color Darkblue; Backcolor Blue"
#ShapeWindow.gb, "Place 50 200; Boxfilled 225 225"
'Set background to Transparent
Call SetBkMode hDCgb, 1
'Release memory
Call ReleaseDC hBgb, hDCbg
'Format and write text
#ShapeWindow.gb, "Font Courier_New 16 86 Bold"
#ShapeWindow.gb, "Color Darkgreen; Place 5 210"
#ShapeWindow.gb, "\Alt-F4 to Close"
Each pixel must be now be read. The background color is black, as defined by
#ShapeWindow.gb, "Down; Fill Black"
so only NON-black pixels will become part of the new region, hRgn. Using a nested loop, the pixels can be searched across and down.
'Read each pixel. Add each pixel to hRgn only if
'color is NOT black (0)
For x = 0 to 250
For y = 0 to 250
If pixelColor(hDCgb, x, y) <> 0 Then
hTempRgn = RectRegion(x, y, x+1, y+1)
newRgn = CombineRgn(hRgn, hRgn, hTempRgn, 3)
Call DelObject hTempRgn
End If
Next y
Next x
Each 2x2 block becomes a region. If the upper left corner pixel is not black, then that newly created tiny region (hTempRgn) becomes part of the final region (hRgn). If the upper left corner pixel is black, then it's not.
A word about searching by pixel. Reading pixel by pixel is a slow process. If you run the demo included in the files archive, be sure to allow 30 - 60 seconds before the background disappears. Larger bitmaps will take considerably longer.
Once the newly formed region, hRgn, is complete, that region is set as the window.
'Set the region as the Window
Call SetWindowRgn hBw, hRgn, 1
As a reminder, API created objects remain in memory until deleted. When closing the window, be sure to release the memory with DelObject.
[closeShapeWindow]
Call DelObject hBw
Close #ShapeWindow
End
The complete program is included in the files archive as ShapedDemo2.bas
Neither graphics nor graphicboxes are required for shaped windows. Simply define the shape using either CreateRectRgn or CreateEllipticRgn and then define the window with SetWindowRgn. You might even use the stylebits _SS_BITMAP and _SS_CENTERIMAGE to show an image as statictext. ShapedDemo3.bas shows an example. This demo requires the boy.bmp bitmap used in the Stylebits Corner of this newsletter issue.
The files ( ShapedDemo1.bas , ShapedDemo2.bas , ShapedDemo3.bas , and boy.bmp ) are included in the zipped archive of this newsletter.
Eddie's Lessons
Beginners Programming